Question

when we touch the a single current wire on streets we get shock but when any bird lies on that single wire it doesnt get shock why?

Answer 1

When we touch the single wire wire we get shock because we are standing on the ground.So electricity passes through our body and hence we get shock.In case of birds they  just stand on the wire and there is no way for electricity to pass through.

Answer 2

because birds legs or even their whole body including cell,tissues does not allow electron an easier route than copper. The electron prefer to travels from good conductor than bad conductor